Riptide by Annabeth Chase
20 parts Complete First in a series of books based on the Percy Jackson books from Annabeth Chase's perspective. This one follows the Lightning Thief but also includes her early years with Thalia and Luke. I am sticking as close to the books as possible though I did borrow a few things from the TV show where it worked better.
Series notes:
Book One: Riptide by Annabeth Chase - Complete
Book Two: Backbiter by Annabeth Chase - Complete
Book Three: Scythe by Annabeth Chase - Complete
Book Four: Palinode by Annabeth Chase - In progress
**Trigger warnings - there are minor amounts of emotional neglect, abuse, spiders and self-harm throughout**